Refining sugar



Patented Jan. 29, 1935 UNITED S ATES anrmnwa SUGAR Pedro Sanchez, Buflalo, N. Y.

Serial No. 719,809

Nam-swing. Application April 9, 1934,

* 10 Claims. (Cl. 12-48) The present invention relates to'a method of refining sugar and more particularly to .a method of treating raw sugar contained in the Juice expressed from sugar cane and sugar beet and other saccharin forming plants whereby solutions, syrups and the like containing such sugars may be clarified and decolorized..

In the purification and production of substantially pure sugar, the sugar going to'the refineries is obtained from crystallization of the juices expressed from the cane, beet andthe like. The sugar crystals are coated with a film of molasses, this type of sugar being generally 'designatedas "raw sugar".

In the refining operations generally practiced prior to this invention, this raw:sugar is cold mixed with water or with raw-sugar washings,-

water to eliminate as much as possible of the adhering molasses. The sugar obtained by this treatment, so-called afllnated or washed sugar, is

further refined and the generally accepted practice heretofore has been to prepare a heavy solution of sugar and water of a sugar content of about 55 Brix, such solutions possessing undesirable color, colloids, waxes, etc., and in addition possessing a certain content of invert sugar, as well as mineral matter designated as ash.

In order to reduce the degree of-color in this syrup or sugar solution this solution is often treated with lime and phosphoric acid or phosphates at raised temperatures in order to render the solution suitable for clarification or filtration.

This clarified" or filtered solution is then decolorized by treating with an activated" carbon at 160 to 180 F., the solution generally being treated with a portion of carbon having already been used once before for this purpose, filtered and thereafter treated with a fresh portion of activated carbon; this latter uponbeing, filtered from the solution is used with a fresh batch of the syrup. In some cases, this activated carbon can be regenerated, its decolorizing properties restored and used again in the process. Another widespread method of decolorizing the solution is to pass the solution at temperatures generally above 160 F., as is the case when treating with activated carbon, through so-called bone char filters. The solution or syrup is generally passed repeatedly through the bone char filter, the number of passages depending upon the amount of color to be removed. The efliciency of the bone char as a decolorizing agent progressively decreases with use and' Murder to restore the activity of the bone char it mustbe revivlfied by heating to high temperatures out of contact of i i In the processes used heretofore large amountsof energy are consumed in maintaining the sugar solution or syrup at elevated temperatures of above 160 Frat thistemperat'ure-an increase in invert sugars is unavoidable, thus reducing the purity of this solution and, therefore, diminish j ing the yield of crystallized sugar. Y

In case of the bone charproce'ss large amoun of char have to' beused in order to obtain the desired decoloration, the amount of char-being 15 at least and in some cases as high as '1 based on the weight of sugar' '-treated. There will be always a large amount oi' bone char and sugar liquor in operation. For this reason a large investment is required in plant and-char equipment, as well as in-char including the char in process and in the regenerating The wash water consumption is very great; a large quantity of hot water being necessary tor the washing of the char filters to remove from the char the absorbed sugar solution to reduce to a minimum the lossjin sucrose. Due toall these facts maintenance, labor, fuel and depreciation on investment are comparatively high. In case of the use of the activated carbon process, the quantities of activated carbons used are considerably: smaller, however, if a revivifiable carbon 'is'used, the revivifyin'g losses are much greater than in case of bone char, and due to the fact that non-sugars are not eliminated with these carbons and that invert sugar is increased, the purity of the decolorized solution and, therefore, the yield of the crystallized sugar is always appreciably lower. The cost of filtrations is comparatively high, as solutions must be ill-- tered at least twice and in most cases special filtering equipment has to be used. The filtration sometimes causes difliculties on account 'of the fineness of the activated carbon which easily passes through the filter cloth. I 45 temperatures prevailingdnlthatilocality; that is, at room temperature and-usually less than 120 F. The present invention further provid'esa method of refining'sugar'wherein-the sugar'may be clarified, decolorized'and filtered: in: substantially-one operation,.producing a syrupthatzmaybe immediately grained in the vacuum tpan or used without further treatment asrefinedsugar syrup. The invention provides .a method of purification- -wherein the amount of. invert sugar originally presentzmaybezsubstantislly reduced and whereby the adverse efiect of the invert sugar upon-the crystallization of-sucroseis diminished;

In practicing the improved refiningjprocedures of my inventlon,.raw'sugar, asobtai'ned'on 'ci'ys-- tallization from the juice; is treated-in theusualway and aillnated or washed sugar obtained.

white syrup whichmay be=nsedlas such-ontrcm' whichthesugar'may hecrystalllzed-as,purewhite refined sugar. By the-lengthy, la-

borious and costly decolorizingandmltering-prowesses g currentlytin 1184? are El To,-eiIect this purlfi'cationthesugar' solution is with chlorine lnran ac-- tive state,- that is a state wherelnthe chlorine possesses the .property of ogidizing or destroying, or. otherwise rendering colorless, the color imparting constituents of the syrup while at thesame time insoluble material *is formed within the :syrup that, moving through the body :of the syrup in a :floccul'ent form and a fornrexposing-a large surface of contact to the syrup,

collects and retains certain colloid matters and deleterious non-sugar materials.

The term chlorine in the active condition", refers to that typeiof chlorine which possess the ability to react upon colored materials changing such materials-to uneolo y ed substances and includes the substances generated when gaseous chlorine isabsorbed. by water which may contain acids or alkalis. Certain ofthese substances containing active chlorine are also obtainable in powder form and fall generally into two classes, those possessing a high chlorine content, in the neighborhood of to available or active chlorine and those possessing up to about 40% active or available chlorine. 'The most suitable substances containing active chlorine are those whose metal ions are. able tovform materials insoluble in sugar solution, or instance calcium, magnesium, barium, strontium, aluminum and other hypochlorites when 'treated'with the proper materials cooperating in the obtainment of the effect desired.

Substances suitable for producing flocculent and insoluble precipitate with the substance containing the active chlorine within the syrup comprise acids and acid salts capable of forming substances insoluble in the syrup which .at the same time remove ash forming mineral matter by combining chemically therewith, as for instance, .phosphoric acid. salts of phosphoric acid. such as mono calcium phosphate, oxalates and borates and in general comprise acids or acid According to my process. this salts which form' a precipitate substantially insolubleinsugar solution.

Byway 015-example-a153- Brix'syrup-ofafllnated sugar isagitated-at room temperature-with-sufll cient calcium hypoohlorite or bleaching powder to give about one tenth-ofone percent'of active chlorinebased upon the weight of :actualsugar treated,althouglr thisquantityrof materialaisillustrativeonlyhs th'e quantity'tozbe-usedwilldepend upon the suganu'sed,:andsufilcienttmono calcium phosphate, in: finely; divided form, .mixed:-and -agi- .t'ated with-the-syrup to produce a fiocculent precipitate of tricalclum phosphate, precipitating .-substantlally all 'of'-the metallic ion addedin the bleaching :powder' and at the same time in an amountsumcientto impart the desired hydrogen ionconcentration-to thessyrup. Under thorough agitation of theisyrup-with-the chemical-reagents the active chlorine chemically decol'orizes the color imparting "materials in the solution while :at the same time very finely distribu'ted gas is liberated, collectsuponand adheres to thessmall' particles of fiocculent precipitate so that upon cessation ofiagitaticn. of the syrup the *buoyant effect of such libei'atedega's causes-all the-flocculent insoluble matter -to rise upwardly :through the .solution-and-collectasazscum uponltheztop-there- :of "leaving the subnatent liquor or .syrupclear, sparkling and substantially water-whita-thecolor --,depending-..on the-amountvof active-chlorineused,

with a layer :ofjinsoluble scum-upon the-surface thereof'ithe quantitywof which representszabout one eighth -tossbhut'wone @twentieth: .of the tote volume of material.

The: time required "for-a completeclarification 1 :depends to a large extent onthe quality of the sugar treated andmay vary from-onehalf :to ten hours. In plants not having enough capacity in regard to settli'ngi tanks, itmay be advisable to filter-theentire'solution together with the'precipi- 'tate, which acts as-filgering medium, according to .any of theknowmmethods, as scones-the desired decolorization is' -obtained. In any case it is ad- -visableto-incorporate a filtering, aid.

This clarifying. and decolorizing step having been performedin suitable settling tanks provided with draw=ofl-means adjacent the bottom thereof the subnatentsyrup is separated-from the insoluble matterand subsequently treated as will be hereafter morefully described while the insoluble matter is; conveyed by suitable pumping or other conveying means and filtered to remove the syrup admixed therewith, the filtrate being added to the bulk of clarified and decolorized syrup for subsequent treatment;

.It is found that if this treatment with hypochlorite be performed in slightly alkaline solution, oxidation of invert sugar is induced thus reducing the content of the invert sugar in the syrup. The formation of colored compounds is 'entirely avoided as the operation is performed or other modes of procedure may be used to effect this result. Thus, where bone black filters are already installed, the clarified and decolorized solutions may be passed through the bone char and dechlorinated while at the same time a small amount of mineral matter is removed from the syrups.

It will be seen from the foregoing that the present invention provides a method of refining sugar that requires a minimum of apparatus, effects considerable saving in consumption of energy since the operation may be effected at room temperatures and eliminates many of the steps currently used in obtaining refined sugar,

since by the procedures of the present invention the steps of clarifying the solution, decolorizing the solution and filtering the solution may be performed at the same time due to the fact that the insoluble matter produced by the interaction of the substance bearing the active chlorine and an acid or acid salt is formed in such manner as to possess a large surface disposed to the action of the solution at which surface gas is formed due to decomposition of the constituents bearing the active chlorine, such as a hypochlorite, which gas moves the insoluble flocculate upwardly through the solution collecting the colloidally dispersed matter, removing coloring matter and collecting upon the top of the solution as a scum which may be readily removed and filtered in any convenient fashion while the subnatent liquid has been clarified, decolorized and filtered, although certain cases may arise where it is advantageous to filter the liquid.

The term substantially-decolorize" as used in the claims, means color elimination producing (a) a substantially water white solution, or (b) a solution having so much of the original color removed as to permit the utilization of the solution for crystallization of white granulated sugar therefrom or as a syrup, or (c) a removal of a major amount oi. the color where the remaining color may, if desired, be removed by P y ical or mechanical means, as for instance, by carbon or by other methods.

What is claimed is:

1. The method of decolorizing afilnated sugar which consists in treating the syrup made from the afiinated sugar with a quantity of a hypochlorite sufilcient to substantially decolorize the solution. mm W 77 2. The method of decolorizing afiinated sugar which consists in treating the syrup made from the animated sugar at room temperature with a quantity of a hypochlorite sumcient to substantially decolorize the solution at room temperature.

3. The step in the method of refining afiinated sugar which comprises substantially decolorizing the syrup made from the aifmated sugar by means of a hypochlorite.

4. The method of refining afiinated sugar which comprises substantially decolorizing the syrup made from the afiinated sugar by means of a quantity of a hypochlorite sufiicient to substantially decolorize the solution and a quantity of material of the group, consisting of an acid and an acid salt, capable of removing substantially all the ash forming material introduced into the solution with the hypochlorite and the acid, or acid salt.

5. The method of refining aflinated sugar which comprises substantially decolorizing the syrup made therefrom by means of a quantity of a hypochlorite sufiicient to substantially decolorize the solution and. a quantity of material of the group consisting of an acid and acid salt capable of forming a salt substantially insoluble in the syrup with substantially all the metallic ion of the hypochlorite and the acid salts.

6. The method of refining affinated sugar which comprises treating the syrup made therefrom with calcium hypochlorite and an acid phosphate in amount sufficient to substantially decolorize the solution and at a pH greater than I, and, thereafter, crystailizing the sugar.

7. The method of decolorizing afilnated sugar which consists in treating the syrup made from the afilnated sugar with calcium hypochlorite and an acid phosphate in amounts sufilcient to substantially decolorize the solution.

8. The method of refining afilnated sugar which consists in decolorizing the syrup made from the afiinated sugar with a quantity of a hypochlorite suificient to substantially decolorize and a quantity of material of the group consisting of an acid or acid salt capable of removing substantially all the ash forming material introduced into the syrup and thereafter dechlorinating the syrup.

9. The method of decolorizing afilnated sugar which consists in treating the syrup made from the aifinated sugar with a quantity of a hypochlorite sufiicient to substantially completely decolorize the solution.

10. The method of decolorizing afiinated sugar which consists in treating the syrup made from the amnated sugar with calcium hypochlorite and a water soluble calcium phosphate in amount Y CERTIFICATE OF CORRECTION.

Patent No. 1,989,156. January 29, 1935.

PEDRO SANCHEZ.

It is hereby certified that error appears in the printed s numbered patent requiring correction as follows: claim 2. strike out the words move to right at room temperature"; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

'Signed and sealed this 19th day of March, A. D. 1935.

pecification of the above Page 3, first column, lines 56-57,

Leslie Frazer (Seal) Acting Commissioner of Patents. 

